The present invention relates to repairing a damaged metal skin of a gas turbine engine part. More particularly, the present invention relates to repairing a cracked metal skin of the engine part by bonding a metal doubler to an underside of the metal skin.
A thin metal layer, such as an aluminum sheet, may be used as an outer skin for a part of a gas turbine engine. The engine part may be formed of a honeycomb core sandwiched between and bonded to two metal skins. The first metal skin may be referred to as a face skin and commonly includes holes or perforations that extend through a thickness of the face skin to the honeycomb. The perforations are provided, in part, for acoustic performance. The second metal skin may be referred to as a back skin and is commonly a non-perforated metal sheet.
The metal parts in the engine may be prone to developing cracks over time. In particular, cracks may form at an edge of a part, starting in the back skin and/or the face skin, due to stress concentrations. A damaged metal skin may be commonly repaired by attaching a replacement metal piece over the damaged portion of the skin. However, in that case, the repair is likely visible and reduces an aerodynamic ability of the part. In other instances, the metal skin may be removed in its entirety and replaced with a new metal sheet, which is expensive and time consuming. There is a need for an improved method and system for repairing cracks at the edge of the metal skin before returning the part to service in a gas turbine engine.